This invention relates to a single lens reflex camera and more particularly to a camera provided with a high speed controlling mechanism for a shutter blind.
A single lens reflex camera known to date is a type attaining focal alignment while visually observing through a finder an image exactly identical with the one being cast on the exposed portion of a photographic film. The conventional single lens reflex camera comprises a shutter blind positioned immediately ahead of an exposure surface; and an optical system consisting of a movable reflector or a fixed semireflector inclined 45.degree. to the axis of an incident light so as to reflect a light beam passing through an object lens 90.degree. upward from said reflector and a pentaprism for conducting the reflected light to a finder. Among cameras of such type, a 35mm single lens reflex camera using a 35mm film is particularly demanded to be as compact as possible and have a smart appearance. Since, however, the aforesaid optical system is used and moreover a film is inserted in a patrone (cartridge), a single lens reflex camera requires a relatively elongate space for the fitting of said patrone, and has its shape naturally expanded, failing to meet the above-mentioned demands.
To describe in further detail, the body of a single lens reflex camera has a movable reflector located at the center in an inclined state. Ahead of the reflector is positioned an object lens and above said reflector is disposed a pentaprism. Behind the reflector is to be disposed an exposure window. On opposite sides of the reflector immediately behind said exposure window are provided a winding shaft and a rewinding shaft for shifting a shutter blind. On the other side of the blind winding and rewinding shafts are provided spaces in which to receive a patrone and a spool respectively so as to allow a photographic film to pass behind the shutter blind. If an attempt is made linearly to arrange the above-mentioned components in the required positions to render a camera body compact without leaving any unnecessary space, then said body will unavoidably have a laterally elongate box shape.
Further, such laterally elongate box-shaped camera body would have to contain the operating and speed controlling mechanisms of a shutter blind, the winding and rewinding mechanisms of a loaded photographic film, a reflector-operating mechanism and further, where an exposure meter is to be used, said meter and an exposure-indicating mechanism. All these components should be disposed near the associated parts not only for miniaturization of a camera body but also for elimination of operating errors. Therefore, according to the prior art single lens reflex camera, the camera top of the camera body contains the operating and speed controlling mechanisms of a shutter blind (said speed controlling mechanism is only associated with the control of the high operating speed of the shutter blind; a mechanism for controlling the low operating speed of the shutter blind requires a separate governor and is positioned at the bottom of the camera body), winding and rewinding mechanisms of a loaded photographic film, an exposure meter and an exposure-indicating mechanism. According to the arrangement on the camera top of the conventional single lens reflex camera, a shutter blind operating mechanism and a mechanism for controlling the high operating speed of the shutter blind are located above the shutter or blind winding shaft; a film winding mechanism above the film winding shaft; and a film rewinding mechanism above the patrone.
A support panel constituting the base of the camera top has a greater height on the patrone side than on the spool side. The reason is that the patrone received in the camera body has an appreciably greater height than 35mm film wound inside of the patrone and said support panel is only required to have a just sufficient height to receive the film.
A mechanism for controlling the operating speed of the shutter blind of a single lens reflex camera constructed as described above consists of a high speed controlling unit and a low speed controlling unit. The former unit is designed to control the higher operating speed of the shutter blind (expressed in a fraction of a second) than that handled by the latter. With a single lens reflex camera, the operating speed of the shutter blind expressed in seconds is separated into two divisions with a time of 1/60 second taken as a border. An operating speed requiring a shorter period than said border time is designated as high and that taking a longer period is treated as low. The high speed controlling mechanism handles a fraction of a second consisting of more decimal places than that handled by the low speed controlling mechanism and consequently is demanded to measure time with an extremely high degree of precision. If, therefore, the high speed controlling mechanism is placed remote from the shutter release shaft, then there will arise extremely undesirable drawbacks that a mechanism for coupling the high speed controlling mechanism with the shutter release shaft will be of complicated arrangement; a larger number of parts will have to be used, possibly leading to operational error; and such complicated coupling arrangement will unavoidably apply a load increased by that extent to high speed operating parts which should be made as light as possible in order to complete movement from the rest position quickly, for example, in two or three-thousandths of a second; and the increased overall weight of said high speed operating parts will lead to a greater inertia thereof, with the resultant failure to effect the aforementioned instantaneous action. To avoid the above-mentioned difficulties, the prior art single lens reflex camera is so designed that the high speed controlling mechanism of the shutter blind is fully separated from the low speed controlling mechanism thereof; namely, the former unit is positioned near a shutter speed setting dial or above the shutter release shaft and the latter is disposed below said shutter release shaft. Placement of the high speed controlling mechanism and the shutter operating mechanism above the shutter release shaft complicates arrangement in that section of a camera body. The required accurate operation of these units which control the movement of the shutter, a decisive factor in determining the performance of a camera, necessarily demands all the associated parts to be finished with extremely high precision in connection with, for example, the shape, size, thickness, engagement holes meshing with operational fulcrums and pivotal sections. Otherwise, there would possibly occur collision between said parts and other components. With the prior art single lens reflex camera, however, such important mechanisms are forcefully incorporated in a limited space with the resultant high manufacturing cost of the associated parts, eventually failing to reduce the price of the camera.
In the conventional single lens reflex camera, concentrated arrangement of various operating mechanisms only at the upper portion of the camera body limits the latitude of its shape and size, and does not admit of a large variety of design for the camera body, nor its miniaturization. Moreover, high precision finish demanded of the operating mechanism has failed to provide an inexpensive single lens reflex camera.